The objective is to confirm experimentally the epidemiologic finding that the selective advantage of the TSD heterozygote is due to possible protection of the heterozygote from tuberculosis. Current experiments measure the phagocytic activity of mouse macrophages for myobacteria in the presence and absence of GM2 ganglioside. BIBLIOGRAPHIC REFERENCE: Myrianthopoulos, N.C. and Melnick, M.: Tay-Sachs disease: a genetic-historical view of selective advantage. In Kaback, M. and Bergsma, D. (Eds.): Tay-Sachs Disease: Screening and Prevention. New York, Alan R. Liss, 1977.